WO2006115104A1 - Dispositif palier a pression dynamique - Google Patents

Dispositif palier a pression dynamique Download PDF

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Publication number
WO2006115104A1
WO2006115104A1 PCT/JP2006/308072 JP2006308072W WO2006115104A1 WO 2006115104 A1 WO2006115104 A1 WO 2006115104A1 JP 2006308072 W JP2006308072 W JP 2006308072W WO 2006115104 A1 WO2006115104 A1 WO 2006115104A1
Authority
WO
WIPO (PCT)
Prior art keywords
bearing
dynamic pressure
peripheral surface
thrust
radial
Prior art date
Application number
PCT/JP2006/308072
Other languages
English (en)
Japanese (ja)
Inventor
Kenji Ito
Isao Komori
Fuminori Satoji
Fuyuki Ito
Yoshiharu Inazuka
Original Assignee
Ntn Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from JP2005121256A external-priority patent/JP4916673B2/ja
Priority claimed from JP2005121253A external-priority patent/JP4937524B2/ja
Priority claimed from JP2005210335A external-priority patent/JP2007024267A/ja
Application filed by Ntn Corporation filed Critical Ntn Corporation
Priority to US11/910,316 priority Critical patent/US8256962B2/en
Priority to CN200680012735XA priority patent/CN101160472B/zh
Publication of WO2006115104A1 publication Critical patent/WO2006115104A1/fr

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C17/00—Sliding-contact bearings for exclusively rotary movement
    • F16C17/10—Sliding-contact bearings for exclusively rotary movement for both radial and axial load
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
    • F16C33/02—Parts of sliding-contact bearings
    • F16C33/04—Brasses; Bushes; Linings
    • F16C33/06—Sliding surface mainly made of metal
    • F16C33/10—Construction relative to lubrication
    • F16C33/1025—Construction relative to lubrication with liquid, e.g. oil, as lubricant
    • F16C33/106—Details of distribution or circulation inside the bearings, e.g. details of the bearing surfaces to affect flow or pressure of the liquid
    • F16C33/107—Grooves for generating pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C17/00—Sliding-contact bearings for exclusively rotary movement
    • F16C17/10—Sliding-contact bearings for exclusively rotary movement for both radial and axial load
    • F16C17/102—Sliding-contact bearings for exclusively rotary movement for both radial and axial load with grooves in the bearing surface to generate hydrodynamic pressure
    • F16C17/107—Sliding-contact bearings for exclusively rotary movement for both radial and axial load with grooves in the bearing surface to generate hydrodynamic pressure with at least one surface for radial load and at least one surface for axial load
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
    • F16C33/02—Parts of sliding-contact bearings
    • F16C33/04—Brasses; Bushes; Linings
    • F16C33/06—Sliding surface mainly made of metal
    • F16C33/10—Construction relative to lubrication
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
    • F16C33/72—Sealings
    • F16C33/74—Sealings of sliding-contact bearings
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
    • F16C33/72—Sealings
    • F16C33/74—Sealings of sliding-contact bearings
    • F16C33/741—Sealings of sliding-contact bearings by means of a fluid
    • F16C33/743—Sealings of sliding-contact bearings by means of a fluid retained in the sealing gap
    • F16C33/745—Sealings of sliding-contact bearings by means of a fluid retained in the sealing gap by capillary action
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K7/00—Arrangements for handling mechanical energy structurally associated with dynamo-electric machines, e.g. structural association with mechanical driving motors or auxiliary dynamo-electric machines
    • H02K7/08—Structural association with bearings
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K7/00—Arrangements for handling mechanical energy structurally associated with dynamo-electric machines, e.g. structural association with mechanical driving motors or auxiliary dynamo-electric machines
    • H02K7/08—Structural association with bearings
    • H02K7/085—Structural association with bearings radially supporting the rotary shaft at only one end of the rotor
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K7/00—Arrangements for handling mechanical energy structurally associated with dynamo-electric machines, e.g. structural association with mechanical driving motors or auxiliary dynamo-electric machines
    • H02K7/08—Structural association with bearings
    • H02K7/086—Structural association with bearings radially supporting the rotor around a fixed spindle; radially supporting the rotor directly
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C2220/00—Shaping
    • F16C2220/02—Shaping by casting
    • F16C2220/04—Shaping by casting by injection-moulding

Definitions

  • the present invention relates to a hydrodynamic bearing device.
  • a hydrodynamic bearing device generates pressure by the dynamic pressure action of fluid generated in a bearing gap due to relative rotation between a bearing member and a shaft member inserted in the inner periphery of the bearing member. Is a non-contact bearing device.
  • This hydrodynamic bearing device has features such as high-speed rotation, high rotation accuracy, and low noise.
  • Information equipment such as magnetic disk devices such as HDD, CD-ROM, CD-R / RW, DVD-ROMZRAM, etc.
  • spindle motors for disk drives in magneto-optical disk devices such as MD and MO, polygon scanner motors for laser beam printers (LBP), projector color wheel motors, and axial fans It is suitable as a bearing device.
  • a radial bearing portion R that supports a shaft member 20 in a radial direction, and a shaft member And a thrust bearing portion T for supporting the shaft in the thrust direction.
  • a dynamic pressure bearing in which a groove for generating dynamic pressure (dynamic pressure groove) is provided on the inner peripheral surface of a cylindrical bearing sleeve 80 is known.
  • a dynamic pressure bearing provided with a pressure groove is known (for example, see Patent Documents 1 and 2).
  • the bearing sleeve 80 is usually fixed at a predetermined position on the inner periphery of the housing 70, and the lubricating oil injected into the inner space of the housing 70 is prevented from leaking to the outside. Therefore, the seal member 90 is often disposed in the opening of the housing 70.
  • Patent Document 1 Japanese Patent Laid-Open No. 2003-65324
  • Patent Document 2 Japanese Patent Laid-Open No. 2003-336636 Disclosure of the invention
  • the hydrodynamic bearing device shown in FIG. 19 has a structure in which the bearing sleeve is fixed to the inner peripheral surface of the housing. Is complicated. In particular, the axial fixing accuracy of the bearing sleeve with respect to the housing also affects the width accuracy of the thrust bearing gap at the thrust bearing, so it must be carefully fixed. Yes.
  • an object of the present invention is to reduce the cost of the hydrodynamic bearing device.
  • a hydrodynamic bearing device includes a shaft member, a shaft member inserted into an inner periphery, and a bearing member formed with a fixing surface for fixing to a bracket on an outer periphery.
  • a radial bearing portion that supports the shaft member in the radial direction by the dynamic pressure action of the lubricating fluid generated in the radial bearing gap between the outer peripheral surface of the shaft member and the inner peripheral surface of the bearing member, and the shaft member in the thrust direction.
  • a thrust bearing portion to be supported and a dynamic pressure generating portion that is formed by molding on the inner peripheral surface of the bearing member facing the radial bearing gap and generates a dynamic pressure action of the lubricating fluid in the radial bearing gap.
  • the bearing member includes a fixing surface for fixing to a bracket (for example, a bracket having a stator coil mounting portion).
  • a radial bearing gap is formed between the inner peripheral surface of the bearing member and the outer peripheral surface of the shaft member facing the bearing member, which generates a dynamic pressure action of a lubricating fluid (lubricating oil, magnetic fluid, air, etc.).
  • a lubricating fluid lubricating oil, magnetic fluid, air, etc.
  • the fixing process of the housing and the bearing sleeve can be omitted, and the cost of the hydrodynamic bearing device can be reduced by reducing the number of parts.
  • the thrust bearing gap width management can be facilitated without the fact that the width of the thrust bearing gap of the thrust bearing portion is affected by the fixing accuracy of the bearing sleeve to the housing as in the prior art.
  • the bearing member by injection molding of a resin or the like.
  • the dynamic pressure generating part of the radial bearing part is formed according to its shape.
  • a molding die having a shape part it is possible to mold the bearing member at the same time as molding of the bearing member, and to further reduce the cost of the hydrodynamic bearing device.
  • a seal space can be formed by a seal member in the opening of the bearing member.
  • This seal space can be formed not only on the inner periphery of the seal member but also on the outer periphery of the seal member.
  • the former is suitable for a structure in which the seal member is fixed to the bearing member.
  • a seal space is formed between the inner peripheral surface of the seal member and the outer peripheral surface of the shaft member.
  • the latter is suitable for a structure in which the seal member is fixed to the shaft member.
  • a seal space is formed between the outer peripheral surface of the seal member and the inner peripheral surface of the bearing member.
  • the hydrodynamic bearing device of the present invention includes a shaft member, a small-diameter inner peripheral surface, and a large-diameter inner peripheral surface.
  • a thrust bearing portion that supports the member in the thrust direction is provided.
  • the bearing member includes a fixing surface for fixing to a bracket (particularly, a bracket having a stator coil mounting portion).
  • a radial bearing gap that generates a dynamic pressure action of a lubricating fluid (lubricating oil, magnetic fluid, air, etc.) is formed between the small-diameter inner peripheral surface of the bearing member and the outer peripheral surface of the shaft member facing the bearing member.
  • the fixing process of the housing and the bearing sleeve can be omitted, and the cost of the hydrodynamic bearing device can be reduced by reducing the number of parts. Further, the width of the thrust bearing gap can be easily managed without the influence of the accuracy of fixing the bearing sleeve with respect to the housing as in the prior art.
  • the seal space can be formed on the outer periphery of the seal member in addition to the inner periphery of the seal member.
  • the former is suitable for the structure in which the seal member is fixed to the bearing member. Therefore, in this case, for example, a seal space is formed between the inner peripheral surface of the seal member and the outer peripheral surface of the shaft member.
  • the latter is suitable for a structure in which the seal member is fixed to the shaft member. In this case, for example, a seal space is formed between the outer peripheral surface of the seal member and the large-diameter inner peripheral surface of the bearing member.
  • the end face of the bearing member and the end face of the seal member can be engaged in the axial direction.
  • the position accuracy in the axial direction of the seal member can be improved by engaging both at the time of assembly.
  • the volume of the seal space may vary.
  • the seal space has a function (buffer function) that absorbs the volume change accompanying the temperature change of the lubricating oil filled in the internal space of the hydrodynamic bearing device. May be a factor.
  • high positional accuracy can be obtained for the seal member by engaging with the end face of the shaft member, so that it is possible to eliminate the fear of force.
  • a space filled with the lubricating fluid in the bearing device may be locally negative pressure due to the influence of processing error or the like.
  • Such negative pressure generation is not preferable because it causes problems such as generation of bubbles in the lubricating fluid and generation of vibration due to generation of bubbles.
  • This fluid flow path is formed, for example, between an axial portion having one end connected to a bearing clearance (thrust bearing clearance) of a thrust bearing portion, and an end surface of the bearing member and an end surface of the seal member. It can be configured with a radial direction portion that communicates the other end of the direction portion and the seal space.
  • the fluid flow path can be formed simultaneously with the molding of the bearing member (bearing sleeve) or by post-processing after the molding of the bearing member.
  • the inner diameter of the fluid flow path is generally very small (several tens of ⁇ m to several hundreds of ⁇ m), it is difficult to form it accurately and stably.
  • the bearing member in order to form a fluid flow path for optimizing the pressure state inside the bearing accurately and stably, the bearing member is opened on both axial sides thereof, and the radial bearing Provide a fluid flow path that allows fluid to flow between both ends of the clearance between the outer peripheral surface of the shaft member including the clearance and the inner peripheral surface of the bearing member, and vary the flow channel area in the axial direction. It was.
  • the present invention is characterized in that the flow passage area of the fluid flow passage provided in the bearing member is varied in the axial direction. According to the powerful configuration, in the region where the flow channel area is at least large in the fluid flow channel, the workability and formability of the fluid flow channel can be improved. In addition, an increase in the amount of fluid retained inside the bearing makes it possible to suppress fluid deterioration. By providing an area in the fluid channel where the channel area is reduced, excessive flow of fluid into the fluid channel can be avoided as much as possible, and the pressure balance inside the bearing can be maintained appropriately.
  • the fluid flow path may be provided with, for example, a first flow path section having a small flow path area and a second flow path section having a large flow path area compared to the first flow path section. .
  • a hydrodynamic bearing device having the fluid flow path for example, a first member that rotatably supports one of a shaft member and a bearing member in a thrust direction via a fluid film formed in a thrust bearing gap.
  • a thrust bearing portion is further provided, and the first thrust bearing portion is provided with a first dynamic pressure generating portion for generating a fluid dynamic pressure action in the thrust bearing gap.
  • the pressure is generated in the pressure generation region of the fluid flow path bearing, the pressure escapes through the opening, and the dynamic pressure effect by the dynamic pressure generation portion may be insufficient. Therefore, it is desirable to open the fluid flow path to the inner diameter side or the outer diameter side avoiding the first dynamic pressure generating portion.
  • the formation region of the first dynamic pressure generating portion is expanded to the inner diameter side in consideration of the necessary shaft diameter of the shaft member. It ’s difficult.
  • the opening of the fluid flow path as the first flow path section having a small flow path area
  • the formation region of the first dynamic pressure generating section can be expanded to the outer diameter side as much as possible. Become. Therefore, the required area can be easily secured at the first dynamic pressure generating portion, and the degree of freedom in bearing design is increased.
  • a second thrust bearing portion that further supports one of the shaft member and the bearing member rotatably in the thrust direction via a fluid film formed in the thrust bearing gap is further provided.
  • the second thrust bearing portion is provided with a second dynamic pressure generating portion for generating a fluid dynamic pressure action in the thrust bearing gap.
  • the outer diameter side of the bearing device has less dimensional restrictions than the inner diameter side. Can be easily expanded to the outer diameter side. Therefore, when the fluid flow path is opened on the inner diameter side of the second dynamic pressure generating portion, it is possible to secure the formation region of the second dynamic pressure generating portion regardless of the opening area. As a result, even when the opening is a second flow path part having a larger flow area than the first flow path part, it is possible to avoid a decrease in the area of the second dynamic pressure generating part due to this. This can further facilitate the bearing design.
  • the fluid channel can take various forms as long as it has a region (for example, the first channel unit and the second channel unit) whose channel areas are different in the axial direction.
  • the fluid flow path has a step between the second flow path portion that opens to one end side in the axial direction of the bearing member and the second flow path portion, and one end side in the axial direction of the bearing member.
  • a first flow path portion that is open to the bottom.
  • a region in which the flow path area gradually decreases from the second flow path portion toward the first flow path portion can be provided over a part or the whole of the axial direction of the fluid flow path.
  • the fluid holding space inside the bearing including these fluid flow paths is usually configured to be able to communicate with the atmosphere via the seal space.
  • the first flow path portion is opened to the outer diameter side from the first dynamic pressure generating portion, it is desirable to provide the first dynamic pressure generating portion on the air blocking side opposite to the seal space.
  • the fluid pressure in the thrust bearing gap can be easily increased as compared with the case where the first dynamic pressure generating portion is provided on the side of the seal space of the bearing member that communicates with the outside air.
  • the bearing member is an integral molded product of resin or metal, the fluid flow path can be formed simultaneously with the bearing member main body when the bearing member is molded.
  • the hydrodynamic bearing device having the above configuration can be preferably used for a motor having a rotor magnet and a stator coil, for example, a spindle motor for HDD.
  • the low cost of the hydrodynamic bearing device can be achieved.
  • the fluid flow path that optimizes the pressure state inside the bearing can be formed accurately and stably.
  • FIG. 1 conceptually shows a configuration example of a spindle motor for information equipment incorporating a fluid dynamic bearing device (fluid fluid dynamic bearing device) 1.
  • This spindle motor for information equipment is used in a disk drive device such as an HDD, and includes a dynamic pressure bearing device 1, a disk hub 3 attached to a shaft member 2 of the dynamic pressure bearing device 1, and a radial gap, for example.
  • the stator coil 4 and the rotor magnet 5 and the bracket 6 that are opposed to each other are provided.
  • the stator coil 4 is attached to, for example, a stator coil attachment portion 6b provided on the outer peripheral surface of the bracket 6, and the rotor magnet 5 is attached to the inner periphery of the disc hub 3.
  • FIG. 2 is a cross-sectional view of the hydrodynamic bearing device 1 used in the spindle motor.
  • the hydrodynamic bearing device 1 includes a shaft member 2, a bearing member 6 with the shaft member 2 inserted on the inner periphery, and a lid member 8 and a seal member 9 fixed to the bearing member 7 as main components. .
  • the description will be made with the side sealed by the seal member 9 of the bearing member 7 as the upper side and the opposite side in the axial direction as the lower side.
  • the first radial bearing portion R1 and the second radial bearing portion R2 are axially arranged between the inner peripheral surface 7a of the bearing member 7 and the shaft portion 2a outer peripheral surface of the shaft member 2. It is provided at a distance.
  • a first thrust bearing portion T1 is provided between the lower end surface 7c of the bearing member 7 and the upper end surface 2bl of the flange portion 2b of the shaft member 2, and the lower side of the inner bottom surface 8al of the lid member 8 and the lower side of the flange portion 2b.
  • a second thrust bearing portion T2 is provided between the end surface 2b2.
  • the shaft member 2 is made of a metal material such as stainless steel, and includes a shaft portion 2a and a flange portion 2b provided separately or separately at the lower end of the shaft portion 2a.
  • a metal material such as stainless steel
  • a flange portion 2b provided separately or separately at the lower end of the shaft portion 2a.
  • resin it is possible to form a metal and resin resin or hybrid structure. it can.
  • the bearing member 7 is formed by resin injection molding.
  • the bearing member 7 includes a sleeve portion 71 in which the shaft portion 2a of the shaft member 2 is inserted on the inner periphery, an upper protruding portion 72 formed on the upper end outer diameter portion of the sleeve portion 71, and a lower end outer diameter of the sleeve portion 71. And a lower projecting portion 73 formed in the portion.
  • the inner peripheral surface of the bearing member 7 is composed of a small-diameter inner peripheral surface 7a, and first and second large-diameter inner peripheral surfaces 7dl and 7d2 having larger diameters.
  • a first large-diameter inner peripheral surface 7dl is formed on the upper projecting portion 72, and a second large-diameter inner peripheral surface 7d2 is formed on the lower projecting portion 73, respectively.
  • the outer diameter of the outer peripheral surface 7b of the bearing member 7 is substantially uniform regardless of the sleeve portion 71 and the upper and lower protrusions 72 and 73.
  • the outer peripheral surface 7b of the bearing member 7 serves as a fixing surface for fixing to the inner peripheral surface 6a of the bracket 6 shown in FIG.
  • the bearing member 7 is fixed to the bracket 6 by, for example, adhesion.
  • the resin forming the bearing member 7 is mainly a thermoplastic resin, such as polysulfone (PSU), polyethersulfone (PES), and polysulfone (P PSU). , Polyetherimide (PEI), etc., as crystalline resin, liquid crystal polymer (LCP), polyetheretherketone (PEEK), polybutylene terephthalate (PBT), polyphenylene Nsulfide (PPS) or the like can be used. Also, the type of filler to be filled in the above-mentioned fat is not particularly limited.
  • filler fibrous filler such as glass fiber, whisker filler such as potassium titanate, scaly form such as my power Fibrous or powdery conductive fillers such as filler, carbon fiber, carbon black, graphite, carbon nanomaterial, metal powder, etc.
  • these fillers may be used alone or in combination of two or more.
  • LCP liquid crystal polymer
  • two upper and lower regions serving as radial bearing surfaces of the first radial bearing portion R1 and the second radial bearing portion R2 are provided apart in the axial direction.
  • a plurality of dynamic pressure grooves G arranged in a herringbone shape, for example, are formed as dynamic pressure generating portions.
  • the upper dynamic pressure groove G corresponding to the first radial bearing portion R1 is formed asymmetrically in the axial direction, in which the axial length X of the upper dynamic pressure groove is the lower dynamic pressure groove. Is slightly larger than the axial length Y ( ⁇ > ⁇ ).
  • the dynamic pressure grooves G in the lower region corresponding to the second radial bearing portion R2 are formed symmetrically in the axial direction, and the axial lengths of the upper and lower dynamic pressure grooves G are equal in the region.
  • the region that becomes the radial bearing surface of the small-diameter inner peripheral surface 7a of the bearing member 7 can be molded simultaneously with the injection molding of the bearing member 7. This is because, for example, a molded part having an uneven shape corresponding to the herringbone shape is formed on the outer periphery of the core rod serving as a molding die, and this core rod is arranged at a prescribed position of the cavity corresponding to the shape of the bearing member 7. This can be done by injecting the grease into the cavity in the state.
  • the molded portion of the core rod and the region serving as the radial bearing surface are unevenly fitted in the axial direction, so that the workability when removing the core rod becomes a problem.
  • the resin is used as the injection material as described above, the resin in the area that becomes the radial bearing surface is elastically deformed as the core rod is pulled out, and then returns to the original shape.
  • the core rod can be smoothly pulled out from the inner periphery of the bearing member 7 without breaking or damaging the pressure groove shape.
  • the inner diameter of the molded product after solidification can be made larger than the outer diameter of the core rod, so that the core rod can be easily pulled out. it can.
  • PPS and PEEK can reduce the anisotropy by selecting the filler, which can improve the dimensional accuracy such as roundness, so that the deformation of the resin during drawing can be suppressed. The pulling workability can be improved.
  • a region to be a thrust bearing surface of the first thrust bearing portion T1 is formed on the lower end surface 7c of the bearing member 7.
  • a plurality of dynamic pressure grooves arranged in a spiral shape, for example, are formed as dynamic pressure generating portions (not shown).
  • This dynamic pressure generating portion can be formed by molding simultaneously with the injection molding of the bearing member 7.
  • any material other than grease can be selected as long as it is a material that can be sufficiently elastically deformed in the region that becomes the radial bearing surface when the core rod is pulled out.
  • the bearing member 7 can also be formed of other soft metal materials and other metal materials (including sintered metal).
  • injection molding or MIM molding of a low melting point metal such as an aluminum alloy
  • the lid member 8 is made of a soft metal material such as brass, other metal materials, or a grease material, and is integrally formed in a bottomed cylindrical shape including a bottom portion 8a and a cylindrical portion 8b protruding above the outer diameter portion of the bottom portion 8a. It is formed.
  • a region serving as a thrust bearing surface of the second thrust bearing portion T2 is formed on the inner bottom surface 8al of the lid member 8. In this region, a plurality of dynamic pressure grooves arranged in a spiral shape, for example, as a dynamic pressure generating portion. Is formed (not shown).
  • the upper end surface of the cylindrical portion 8b is brought into contact with the lower end surface 7c of the bearing member 7 (the lower end surface of the sleeve portion 71), whereby each thrust of the first thrust bearing portion T1 and the second thrust bearing portion T2 is obtained.
  • the bearing gap is set to a specified width.
  • the lid member 8 is fixed to the bearing member 7 by fixing the outer peripheral surface of the cylindrical portion 8b to the large-diameter inner peripheral surface 7d2 of the lower protrusion 73 of the bearing member 7 by means such as adhesion or press fitting.
  • the lid member 8 can be integrated with the bearing member 7 by fixing them together by welding (for example, ultrasonic welding).
  • Each of the seal members 9 is formed in a ring shape from a soft metal material such as brass, other metal materials, or a resin material, and is bonded to the large-diameter inner peripheral surface 7dl of the upper protruding portion 72, for example. Therefore, it is fixed. At this time, the lower end surface 9b of the seal member 9 is brought into contact with the upper end surface 7e of the bearing member 7 (the upper end surface of the sleeve portion 71) and is engaged with each other in the axial direction.
  • a soft metal material such as brass, other metal materials, or a resin material
  • the inner peripheral surface 9a of the seal member 9 forms a seal space S having a predetermined volume with the outer peripheral surface of the shaft portion 2a.
  • the inner peripheral surface 9a of the seal member 9 is formed in a tapered surface shape that gradually increases in diameter toward the outside of the bearing member 7. Therefore, the seal space S is a tapered shape that gradually decreases in the direction toward the inside of the bearing member. Presents. Accordingly, the lubricating oil in the seal space S is drawn toward the direction in which the seal space S becomes narrower due to the drawing action by the capillary force, and as a result, the upper end opening of the bearing member 7 is sealed.
  • the interior space of the bearing member 7 sealed by the seal member 9 is filled with, for example, lubricating oil as a lubricating fluid.
  • the seal space S also has a buffer function that absorbs the volume change accompanying the temperature change of the lubricating oil filled in the internal space of the bearing member 7, and the oil level is always in the seal space S.
  • the inner peripheral surface 9a of the seal member 9 may be a cylindrical surface, and the outer peripheral surface of the shaft portion 2a facing the cylindrical member may be formed into a tapered surface. As a result, the sealing effect is further enhanced.
  • the two upper and lower regions of the small-diameter inner peripheral surface 7a of the bearing member 7 that are the radial bearing surfaces face the outer peripheral surface of the shaft portion 2a via a radial bearing gap.
  • the region of the lower end surface 7c (the lower end surface of the sleeve portion 71) of the bearing member 7 that is the thrust bearing surface is opposed to the upper end surface 2bl of the flange portion 2b through a predetermined thrust bearing gap, and the lid member 8
  • the area that becomes the thrust bearing surface of the inner bottom surface 8al faces the lower end surface 2b2 of the flange portion 2b through a predetermined thrust bearing gap.
  • the first thrust bearing portion T1 and the second thrust bearing portion T2 are configured to support the shaft member 2 in a non-contact manner so as to be rotatable in the thrust direction.
  • a fluid flow path 10 for communicating the bearing gap of the first thrust bearing portion T1 with the seal space S is formed.
  • the fluid flow path 10 includes axially extending portions (axial portions) 1 Oa that pass through the sleeve portion 71 of the bearing member 7 and open to the upper and lower end surfaces 7e and 7c thereof, and the upper end of the axial direction portion 10a and the seal space. It is composed of a radially extending portion (semi-radial portion) 10b that communicates with S.
  • the axial portion 10a is opened in the space between the outer peripheral surface of the flange portion 2b and the inner peripheral surface of the lid member 8 is illustrated.
  • the radial direction portion 10b can be constituted by a groove formed on the lower end surface 9b of the seal member 9 as well as a groove formed on the upper end surface 7e of the sleeve portion 71, for example.
  • the method of forming the axial portion 10a is arbitrary.
  • the resin is injected in a state where the molding pin is stretched over the cavity, and then demolding is performed. Sometimes it can be formed by a method of removing the forming pin.
  • the axial portion 10a can be formed by machining after injection molding.
  • the radial portion 10b can be formed, for example, simultaneously with injection molding of the bearing member 7 or by machining after injection molding.
  • the dynamic pressure groove G of the first radial bearing portion R1 is formed to be axially asymmetric, and the axial dimension X of the upper region is larger than the axial dimension Y of the lower region. Yes. Therefore, when the shaft member 2 rotates, the pulling force (bombing force) of the lubricating oil by the dynamic pressure groove G is relatively larger in the upper region than in the lower region.
  • the lubricating oil filled in the gap between the small-diameter inner peripheral surface 7a of the bearing member 7 and the outer peripheral surface of the shaft portion 2a flows downward, and the first thrust bearing portion T1 It circulates through the path of the thrust bearing gap ⁇ the axial portion 10a of the fluid flow path 10 ⁇ the radial portion 10b, and is drawn into the radial bearing gap of the first radial bearing portion R1 again.
  • the phenomenon that the pressure of the lubricating oil filled in the bearing member 7 becomes a negative pressure locally can be prevented.
  • the dynamic pressure bearing device 1 described above has the shaft member 2, the bearing member 7, the lid member 8, and the seal member 9 as main components, which is compared with the conventional product shown in FIG. The number of parts can be reduced.
  • the bearing sleeve and housing fixing process which is required in the assembly process of the conventional product, is not necessary. Therefore, the cost of the hydrodynamic bearing device 1 can be reduced.
  • the width accuracy of the thrust bearing gap between the thrust bearing portion Tl and the flange 2 depends on the molding accuracy of the shaft member 7 and the lid member 8 as well as the assembling accuracy. Therefore, if each of the shaft member 7 and the lid member 8 is molded with sufficient accuracy, the gap width of the thrust bearing gap can be set with high accuracy, and management of the gap width can be facilitated. Further, since the upper end surface 7e of the bearing member 7 and the lower end surface 9b of the seal member 9 are in contact with each other in the axial direction, the positional accuracy of the seal member 9 in the axial direction can be improved.
  • FIG. 3 shows another configuration of the hydrodynamic bearing device 1.
  • the hydrodynamic bearing device 1 is different from the hydrodynamic bearing device shown in FIG. 2 in that the lid member 8 has a flat plate shape and is fixed to the large-diameter inner peripheral surface 7d2 of the lower protrusion 73. is there.
  • a stepped portion 7f is formed on the large-diameter inner peripheral surface 7d2, and the outer diameter portion of the lid member 8 is engaged with the stepped portion 7f, whereby the clearance width of the thrust bearing clearance of the thrust bearing portion Tl and ⁇ 2 Can be managed with high accuracy.
  • FIG. 4 shows another configuration of the hydrodynamic bearing device 1.
  • This hydrodynamic bearing device 1 differs from the hydrodynamic bearing device shown in FIGS. 2 and 3 in that the thrust bearing portion is composed of a pivot bearing that is not a hydrodynamic bearing.
  • the pivot bearing has a structure in which the spherical shaft end 2c of the shaft member 2 is brought into contact with the inner bottom surface 8al of the lid member 8 (or another low frictional member disposed on the inner bottom surface al).
  • a thrust bearing portion T that supports the member 2 in the thrust direction is configured.
  • both of the forces illustrating the case where the lid member 8 is integrally formed with the bearing member 7 can be used as separate members.
  • a fluid flow path 10 is provided in the same manner as the hydrodynamic bearing device shown in FIGS. 2 and 3, and the space formed between the shaft end 2c of the shaft member 2 and the bearing member 7 is sealed. It is also possible to communicate with the space S.
  • FIG. 5 shows another configuration of the hydrodynamic bearing device 1.
  • This dynamic pressure bearing device differs from the dynamic pressure bearing device shown in FIG. 2 mainly in that the seal member 9 is fixed to the shaft member 9 on the rotation side.
  • a seal space S is formed between the outer peripheral surface 9c of the seal member 9 and the large-diameter inner peripheral surface 7dl of the upper protrusion 72.
  • the lower end surface 9 of the seal member 9 b opposes the upper end surface 7e of the bearing member 7 via a thrust bearing gap, and constitutes a second thrust bearing portion T2.
  • the lower end surface 9b of the seal member 9 and the upper end surface 7e of the bearing member 7 are engaged in the axial direction.
  • the outer peripheral surface 9c of the seal member 9 is formed in a taper surface shape that is gradually reduced in diameter toward the outside of the bearing member 7, so that the seal space S has a tapered shape that is gradually reduced toward the inside of the bearing member 7.
  • the seal space S is formed on the outer peripheral surface 9a side of the seal member 9, the seal space S (in order to secure the volume necessary for obtaining a predetermined buffer function in the seal space S ( The axial dimension of the seal member 9) can be made smaller than that of the hydrodynamic bearing device shown in FIG. 2, and therefore the axial dimension of the hydrodynamic bearing device 1 can be reduced.
  • the axial portion 10a is provided as the fluid flow path 10, and the thrust bearing gap of the first thrust bearing portion T1 is sealed through this axial portion 10a. It communicates with space S.
  • the lubricating oil that has flowed downward in the gap between the inner peripheral surface 7a of the bearing member 7 and the outer peripheral surface of the shaft portion 2a becomes the thrust bearing clearance ⁇ shaft of the first thrust bearing portion T1.
  • the direction portion 10a circulates through the path of the thrust bearing gap of the second thrust bearing portion T2, and is drawn again into the radial bearing gap of the first radial bearing portion R1.
  • the pulling force (bombing force) of the lubricating oil into the inner diameter side by the dynamic pressure groove G of the second thrust bearing portion T2 also acts on the lubricating oil in the radial bearing gap of the first radial bearing portion R1. Even if the differential pressure of the pull-in force in the first radial bearing portion R1 is relatively low, good fluid circulation of the lubricating oil is ensured. As a result, the axial asymmetry in the dynamic pressure groove G of the first radial bearing portion R1 can be made smaller than before. For example, the axial dimension X in the upper region of the dynamic pressure groove G can be made smaller than before and the bearing can be reduced. The axial dimension of the sleeve 8 can be reduced.
  • FIG. 6 shows a hydrodynamic bearing device 1 having another configuration.
  • This hydrodynamic bearing device 1 is sealed with a lid member 8 that is formed by simply sealing the upper end opening of the bearing member 7 with the first seal member 9. 5 is different from the hydrodynamic bearing device shown in FIG. 5 in that the opening on the closed side is also sealed with the second seal member 11.
  • a first seal space S1 is formed between the outer peripheral surface 9c of the first seal member 9 and the large-diameter inner peripheral surface 7dl of the upper protruding portion 72, and the outer peripheral surface 11c of the second seal member 11 and the lower protruding portion
  • a second seal space S2 is formed between the large-diameter inner peripheral surface 7d2 of the portion 72.
  • Both the seal spaces Sl and S2 are in communication with each other via the axial portion 10a of the fluid flow path 10.
  • the lower end surface l ib of the second seal member 11 is opposed to the lower end surface 7c of the bearing member 7 via a thrust bearing gap, and constitutes the first thrust bearing portion T1. .
  • the outer peripheral surface 11c of the second seal member 11 has a tapered surface shape in which the diameter gradually increases toward the inner direction of the bearing member 7, whereby the second seal
  • the space S2 has a tapered shape that is gradually reduced in the inner direction of the bearing member.
  • the bearing device since the seal spaces Sl and S2 are formed in the opening portions at both ends of the bearing member 7, compared to the hydrodynamic bearing device 1 shown in Fig. 5 in which the seal space S is formed only in the upper end opening portion, the bearing device The overall buffer function can be enhanced. Accordingly, the volumes of the individual seal spaces Sl and S2 can be further reduced, and the axial dimensions of the seal members 9 and 11 can be reduced to further reduce the axial dimensions of the hydrodynamic bearing device.
  • the radial bearing portions Rl, R2 and the thrust bearing portions Tl, ⁇ 2 are exemplified as the configuration in which the dynamic pressure action of the lubricating oil is generated by the dynamic pressure grooves having a helical bone shape or a spiral shape.
  • Force As radial bearings Rl and R2, so-called step bearings can be adopted as multi-arc bearings, and as thrust bearings Tl and ⁇ 2, so-called step bearings with dynamic pressure grooves arranged radially, so-called wave bearings ( The step type becomes a wave type).
  • the dynamic pressure grooves G of the first and second radial bearing portions Rl, R2 are formed in the small-diameter inner peripheral surface 7a of the sleeve portion 71 is exemplified.
  • G can also be formed on the outer peripheral surface of the shaft portion 2a of the shaft member 2.
  • the upper and lower two regions that are the radial bearing surfaces of the first radial bearing portion R1 and the second radial bearing portion R2 are provided on the outer peripheral surface of the shaft portion 2a of the shaft member 2 so as to be separated from each other in the axial direction.
  • a plurality of dynamic pressure grooves G arranged in a herringbone shape, for example, are formed in each region as dynamic pressure generating portions.
  • the upper and lower regions of the outer peripheral surface of the shaft portion 2a that are the radial bearing surfaces are formed by forging, rolling, etching, or printing. Can be formed.
  • the two upper and lower regions of the outer peripheral surface of the shaft portion 2a that are the radial bearing surfaces face the small inner diameter surface 7a of the bearing member 7 through the radial bearing gap, and the radial Lubricating oil dynamic pressure is generated in the bearing gap.
  • FIGS. 7 and 8 show an example in which one or both of the radial bearing portions Rl and R2 is formed of a multi-arc bearing.
  • the sleeve portion 71 is constituted by three arcuate surfaces 7al as a region dynamic pressure generating portion that becomes a radial bearing surface of the small-diameter inner peripheral surface 7a (so-called three-arc bearing).
  • the centers of curvature of the three circular arc surfaces 7al are offset by the same distance from the axial center O force of the bearing member 7 (shaft member 2).
  • the radial bearing gap has a shape gradually reduced in a wedge shape in both circumferential directions.
  • the bearing member 7 and the shaft member 2 rotate relative to each other, the lubricating oil in the radial bearing gap is pushed into the minimum gap side reduced in a wedge shape according to the direction of the relative rotation, and the pressure increases. .
  • the bearing member 7 and the shaft member 2 are supported in a non-contact manner by such a dynamic pressure action of the lubricating oil.
  • a deeper axial groove called a separation groove may be formed at the boundary between the three circular arc surfaces 7al.
  • Fig. 8 shows another example of the multi-arc bearing.
  • the radial bearing gap is gradually reduced to a wedge shape in one circumferential direction. have.
  • the multi-arc bearing having such a configuration may be referred to as a taper bearing.
  • a deeper axial groove 7a3 called a separation groove is formed at a boundary portion between the three arcuate surfaces 7al.
  • the predetermined regions on the minimum gap side of the three circular arc surfaces 7 al are each formed by concentric arcs with the center O of the bearing member 7 (shaft member 2) as the center of curvature. (Also called taper 'flat bearings
  • such a dynamic pressure generating portion including the multi-arc surface 7al can be molded simultaneously with the injection molding of the bearing member 7.
  • the multi-arc surface 7al and the core rod molding part Since the concave / convex fitting in the axial direction does not occur between the two, the core rod can be smoothly pulled out from the inner periphery of the bearing member 7 at the time of demolding. Therefore, as a material characteristic of the bearing member 7, the importance of elastic deformation is reduced, and the degree of freedom in material selection is increased.
  • a dynamic pressure groove as a dynamic pressure generating portion can be formed on one or both of both end faces 2bl and 2b2 of the portion 2b.
  • FIG. 9 schematically shows a configuration example of a spindle motor for information equipment incorporating the fluid dynamic bearing device 1.
  • This spindle motor is used in a disk drive device such as an HDD, and is provided with a hydrodynamic bearing device 1 that rotatably supports a shaft member 3 having a shaft 2 and a knob portion 10 in a non-contact manner, for example, in the radial direction.
  • a stator coil 4 and a rotor magnet 5 which are opposed to each other through a gap, and a bracket 6 are provided.
  • the stator coil 4 is attached to the outer diameter side of the bracket 6, and the rotor magnet 5 is attached to the outer periphery of the hub portion 10 of the shaft member 3.
  • the bearing member 7 of the fluid dynamic bearing device 1 is fixed to the inner periphery of the bracket 6.
  • the hub portion 10 of the shaft member 3 holds a disk-shaped information recording medium (hereinafter simply referred to as a disk) such as a magnetic disk.
  • a disk disk-shaped information recording medium
  • the spindle motor configured as described above, when the stator coil 4 is energized, the rotor magnet 5 is rotated by the exciting force generated between the stator coil 4 and the rotor magnet 5, and accordingly, the shaft member 3 and The disc held on the hub portion 10 of the shaft member 3 rotates integrally with the shaft 2.
  • FIG. 10 shows the hydrodynamic bearing device 1 in an enlarged manner.
  • the hydrodynamic bearing device 1 mainly includes a shaft member 3 and a bearing member 7 capable of accommodating the shaft 2 of the shaft member 3 on the inner periphery.
  • the bearing member 7 housing portion 9) formed at both ends in the axial direction will be described below with the side sealed by the lid member 11 being the lower side and the side opposite to the sealing side being the upper side. To do.
  • the shaft member 3 includes, for example, a hub portion 10 disposed on the opening side of the bearing member 7 and a shaft 2 extending in the rotation axis direction from the radial center of the hub portion 10.
  • the hub portion 10 is formed of metal or grease, and includes a disc portion 10a that covers the opening side (upper side) of the bearing member 7, a cylindrical portion 10b in which the outer peripheral force of the disc portion 10a extends downward in the axial direction, 10b It is composed of a disk mounting surface 10c and a flange lOd provided on the outer periphery. A disk (not shown) is fitted on the outer periphery of the disk portion 10a and placed on the disk mounting surface 10c. Then, the disc is held on the hub portion 10 by appropriate holding means (such as a clamper) not shown.
  • appropriate holding means such as a clamper
  • the shaft 2 is formed integrally with the hub portion 10, and is provided with a flange portion 2b as a separate member at the lower end thereof.
  • the flange portion 2b is made of metal and is fixed to the shaft 2 by means such as screw connection.
  • the shaft 2 and the hub portion 10 are integrally formed of metal or grease as described above, and the shaft 2 and the hub portion 10 can be formed separately.
  • the shaft 2 can be made of metal, and the shaft member 3 can be molded with the grease integrally with the hub portion 10 by using the metal shaft 2 as an insert part.
  • the bearing member 7 has a shape in which both ends in the axial direction are opened, is a substantially cylindrical sleeve portion 8, and a housing that is positioned on the outer diameter side of the sleeve portion 8 and holds the sleeve portion 8 on the inner periphery. Part 9 is mainly provided.
  • the bearing member 7 is injection molded with a resin composition based on a crystalline resin such as LCP, PPS, or PEEK, or an amorphous resin such as PSU, PES, or PEI.
  • the sleeve portion 8 and the nosing portion 9 are formed on the body.
  • a region where a plurality of dynamic pressure grooves are arranged as a radial dynamic pressure generating portion is formed on the entire inner surface or part of the cylindrical surface region of the inner peripheral surface 8a of the sleeve portion 8.
  • this hydrodynamic bearing device for example, as shown in FIG. 11, two regions having a plurality of hydrodynamic grooves 8al and 8a2 arranged in a herringbone shape are formed apart in the axial direction.
  • the dynamic pressure groove 8al is formed axially asymmetric with respect to the axial center m (the axial center of the region between the upper and lower inclined grooves).
  • the axial dimension XI of the upper area above m is larger than the axial dimension X2 of the lower area. Therefore, when the shaft member 3 rotates, the lubricating oil in the radial bearing gap is pushed downward by the asymmetric dynamic pressure groove 8al.
  • a first thrust bearing surface 8b is provided on the entire lower surface or a partial annular surface region of the sleeve portion 8. As shown in FIG. 13, for example, as shown in FIG. 13, a region in which a plurality of dynamic pressure grooves 8bl are arranged in a spiral shape is formed on the first thrust bearing surface 8b.
  • This first thrust bearing surface 8b (dynamic pressure groove 8bl formation region) faces the upper end surface 2bl of the flange portion 2b, and the first thrust bearing is between the upper end surface 2bl when the shaft 2 (shaft member 3) rotates. Thrust of part T1 (See Fig. 10).
  • the housing portion 9 located on the outer diameter side of the sleeve portion 8 has a substantially cylindrical shape, and its axial width is longer than that of the sleeve portion 8.
  • the housing portion 9 has a form in which the lower end in the axial direction protrudes further to the lower end side than the lower end surface (first thrust bearing surface 8b) of the sleeve portion 8.
  • the end face (upper end face) on one end side of the housing part 9 is located slightly above the upper end face 8c of the sleeve part 8 continuing to the inner periphery thereof, and the second thrust bearing is provided on the entire surface or part of the annular region.
  • Surface 9a is provided.
  • a plurality of dynamic pressure grooves 9a 1 are formed on the second thrust bearing surface 9a as a second thrust dynamic pressure generating portion in a spiral shape (the dynamic pressure grooves 8b 1 shown in FIG.
  • the regions are arranged in the opposite direction.
  • This second thrust bearing surface 9a (dynamic pressure groove 9al formation region) faces the lower end surface lOal of the disk portion 10a of the hub portion 10, and when the shaft member 3 rotates, a second later described between the lower end surface lOal and the lower end surface lOal.
  • a thrust bearing gap is formed in the thrust bearing portion T 2 (see FIG. 10).
  • the lid member 11 that seals the lower end side of the housing part 9 (bearing member 7) is made of metal or grease, and is fixed to a step part 9b provided on the inner peripheral side of the lower end of the housing part 9.
  • the fixing means is not particularly limited, and for example, means such as adhesion (including loose adhesion, press-fit adhesion), press-fit, welding (for example, ultrasonic welding), welding (for example, laser welding), a combination of materials, It can be appropriately selected according to the required assembly strength, sealing property, and the like.
  • a tapered seal surface 9c is formed on the outer periphery of the housing portion 9 so as to gradually increase in diameter by upward force.
  • This taper-shaped sealing surface 9c is between the inner peripheral surface 10bl of the cylindrical portion 10b and an annular shape whose radial dimension is gradually reduced from the sealing side (downward) to the opening side (upward) of the bearing member 7.
  • the seal space S is formed. This seal space S communicates with the outer diameter side of the thrust bearing gap of the second thrust bearing portion T2 when the shaft 2 and the hub portion 10 are rotated.
  • one or a plurality of communication holes 12 as fluid flow paths penetrating the bearing member 7 in the axial direction are formed in the radial intermediate portion of the bearing member 7.
  • the communication holes 12 are provided, for example, at four locations at equal intervals in the circumferential direction, and open at the lower end to the outer diameter side of the first thrust bearing surface 8b of the sleeve portion 8 (see FIG. 13). Further, the communication hole 12 opens at the upper end on the inner diameter side of the second thrust bearing surface 9a of the housing portion 9 (see FIG. 12). This makes the bearing When the inside of the device is filled with the lubricating oil described later, the lubricating oil can flow between the thrust bearing gaps of both thrust bearing portions Tl and ⁇ 2.
  • both ends of the gap between the outer peripheral surface 2a of the shaft 2 and the inner peripheral surface 8a of the sleeve portion 8 including the radial bearing gaps located between the axial end surfaces 8b and 8c of the sleeve portion 8 or the inner diameter side thereof. Between them (see Figure 10).
  • the communication hole 12 has a configuration in which the cross-sectional area is varied in the axial direction, and the second thrust has a relatively small diameter (small diameter portion 12a) on the opening side of the lower end surface including the first thrust bearing surface 8b.
  • a relatively large diameter (large diameter portion 12b) is formed on the opening side of the upper end surface including the bearing surface 9a.
  • These communication holes 12 can be formed simultaneously with the formation of the bearing member 7 when the bearing member 7 is injection-molded with a resin, for example.
  • a forming pin having a shape corresponding to the communication hole 12 described above, here, an outer diameter corresponding to the small diameter portion 12a and the large diameter portion 12b is used.
  • a forming pin is used for forming the communication hole 12.
  • the inside of the hydrodynamic bearing device 1 having the above-described configuration is filled with lubricating oil, and the oil level of the lubricating oil is always maintained in the seal space s.
  • this hydrodynamic bearing device for example, as shown in FIG. 10, the communication hole 12 and regions including the thrust bearing gaps of the thrust bearing portions T 1 and T 2 respectively formed on both axial ends of the communication hole 12 (FIG. 10)
  • the area indicated by the dot pattern is filled with lubricating oil.
  • Lubricating oil provided to a hydrodynamic bearing device for a disk drive device such as an HDD is considered a temperature change during its use or transportation. Ester lubricants excellent in low evaporation rate and low viscosity, such as dioctyl sebacate (DOS), dioctyl azelate (DOZ) and the like can be suitably used.
  • DOS dioctyl sebacate
  • DOZ dioctyl azelate
  • the inner peripheral surface 8a of the sleeve portion 8 serves as a radial bearing surface (the upper and lower dynamic pressure grooves 8al, 8a2 The formation region) is opposed to the outer peripheral surface 2a of the shaft 2 via a radial bearing gap.
  • the lubricating oil in the radial bearing gap is pushed toward the axial center of the dynamic pressure grooves 8al and 8a2, and the pressure rises.
  • the first radial bearing portion R1 and the second radial bearing portion R2 that support the shaft 2 in a non-contact manner in the radial direction are configured.
  • Oil films of lubricating oil are formed by the pressure action.
  • the first thrust bearing portion T1 and the second thrust bearing portion T2 that support the shaft member 3 in the thrust direction in a non-contact manner are constituted by the pressure of these oil films.
  • the second thrust bearing located at the lower end of the bearing member 7 (sleeve portion 8) via the communication hole 12
  • the thrust bearing gap of the portion T2 and the seal space S formed on the opening side of the bearing member 7 (the outer diameter side of the housing portion 9) are in communication with each other. According to this, for example, if for some reason the fluid (lubricating oil) pressure on the second thrust bearing portion T2 side increases excessively and is reduced! It is possible to stably support non-contact.
  • the first thrust bearing surface 8b (dynamic pressure) of the sleeve portion 8 is provided by providing the small diameter portion 12a as the first flow path portion on the thrust bearing clearance side (lower end side) of the first thrust bearing portion T1.
  • the area of the groove 8b 1 formation area) can be expanded in the outer diameter direction.
  • the radial load of the rotating body (shaft member 3) accompanying the increase in the number of disks can be supported by the thrust bearing portion, and stable rotation accuracy can be obtained.
  • the small-diameter portion 12a on the opening side of the thrust bearing gap of the first thrust bearing portion T1 of the communication hole 12 the escape of fluid in the thrust bearing gap to the fluid flow path (communication hole 12) is minimized.
  • the communication hole 12 having the large diameter portion 12b is formed by the injection molding of the bearing member 7, so that at least a portion corresponding to the large diameter portion 12b
  • the rigidity or strength can be increased.
  • the axial width of the small diameter portion 12a can be reduced by providing the large diameter portion 12b, the bending rigidity of the molding pin at the location corresponding to the small diameter portion 12a can be improved. Therefore, when the diameter of the communication hole 12 (fluid flow path) is reduced with the aim of reducing the size of the hydrodynamic bearing device 1, the overall outer diameter of the pin corresponding to the inner diameter of the open communication hole 12 is reduced. Even if it is made smaller, the rigidity and strength of the pin can be secured. Therefore, it is possible to easily cope with the downsizing of the hydrodynamic bearing device 1 and the motor equipped with the hydrodynamic bearing device 1.
  • the fluid channel is formed by this method, the generation of chips and the like in the channel after processing can be suppressed, so that cleaning for removing this kind of unnecessary material can be simplified or simplified. It can be omitted and is advantageous in terms of cost.
  • the dynamic pressure groove 8al of the first radial bearing portion R1 is formed axially asymmetric (XI> X2) with respect to the axial center m! (Refer to Fig. 11)
  • the lubricating oil pull-in force (bombing force) by the dynamic pressure groove 8al is relatively larger in the upper region than in the lower region.
  • the lubricating oil filled between the inner peripheral surface 8a of the sleeve portion 8 and the outer peripheral surface 2a of the shaft 2 flows downward, and the thrust bearing of the first thrust bearing portion T1 It circulates in the path of clearance ⁇ communication hole 12 ⁇ axial clearance between the upper end surface 8c and the lower end surface lOal, and is drawn again into the radial bearing clearance of the first radial bearing portion R1.
  • the bearing member 7 is provided with the axial communication hole 12 so that the lubricating oil flows and circulates in the bearing internal space including the radial bearing gap, thereby the bearing interior including the bearing gaps. The pressure balance is maintained properly.
  • the dynamic pressure bearing device of the present invention may adopt other configurations without being limited to the above configuration.
  • another configuration example of the hydrodynamic bearing device will be described.
  • parts and members that have the same configuration and action as the hydrodynamic bearing device shown in FIG. 10 are given the same reference numerals, and redundant descriptions are omitted.
  • the shaft member 22 includes the shaft 22a and the shaft 22a.
  • a flange portion 22b provided integrally or separately is provided at the lower end.
  • the bearing member 27 includes a sleeve portion 8 and a housing portion 29 that is positioned on the outer diameter side of the sleeve portion 8 and formed integrally with the sleeve portion 8.
  • the nose and udging portion 29 has a shape in which both ends in the axial direction protrude upward and downward in the axial direction from both end surfaces 8b and 8c of the sleeve portion 8.
  • An annular seal portion 24 is fixed to the inner periphery of the upper end protruding portion 29a with its lower end surface 24b in contact with the upper end surface 8c of the sleeve portion 8.
  • An annular seal space S2 is formed between the inner peripheral surface 24a of the seal portion 24 and the outer peripheral surface 22al of the shaft 22a facing this surface.
  • a lid member 25 that seals the lower end side of the bearing member 27 is fixed to the inner periphery of the lower end protruding portion 29b of the housing portion 29.
  • a second thrust bearing surface 25a is provided in a partial annular region of the upper end surface of the lid member 25.
  • a dynamic pressure groove array region shown in FIG. 12 is formed as a thrust dynamic pressure generating portion on the second thrust bearing surface 25a.
  • a protruding portion 25b protruding upward is provided on the outer periphery of the second thrust bearing surface 25a.
  • the lid member 25 is fixed to the lower end protruding portion 29b with the contact surface 25bl positioned at the upper end of the protruding portion 25b being in contact with the lower end surface of the sleeve portion 8.
  • the fluid flow path passes through the bearing member 27 in the axial direction, and has a communication hole 12 that opens on both sides in the axial direction (both end surfaces 8b and 8c side of the sleeve portion 8), and a lid. It is provided on the contact surface 25bl of the member 25, and is constituted by a radial groove 25c that communicates a lower end opening side of the communication hole 12 and a thrust bearing gap Tl1, T12 described later.
  • the lower end surface 24b of the seal portion 24 is formed with one or a plurality of radial grooves 24b 1 that connect the lower end opening side of the communication hole 12 and the upper end of the radial bearing gap of the first radial bearing portion R1. !
  • the first thrust bearing surface (lower end surface) 8b of the sleeve portion 8 and the upper end surface 22bl of the flange portion 22b of the shaft member 22 are arranged.
  • a first thrust bearing portion T11 is formed, and a second thrust bearing portion T12 is formed between the second thrust bearing surface 25a of the lid member 25 and the lower end surface 22b2 of the flange portion 22b.
  • the hydrodynamic bearing device 31 having the configuration shown in Fig. 15 is mainly composed of the sleeve portion 8 and the housing portion 9 that constitute the bearing member 7, and the hydrodynamic bearing device 1 shown in Fig. 10. And the configuration is different.
  • the sleeve portion 8 is formed of, for example, a metal such as brass or aluminum, or is formed of a porous material of sintered metal.
  • the sleeve portion 8 is formed of a sintered metal porous body mainly composed of copper, and its outer peripheral surface 8d is attached to the inner peripheral surface 9d of the udging portion 9 and press-fitted. Or, it is fixed by means such as welding.
  • the shaft 2 is connected to the flange portion 2b, for example, although not shown. It can also be a straight shape that does not have any.
  • the housing part 9 forms a bottomed cylindrical shape by integrally forming the lid member 11 as a bottom part.
  • One or a plurality of axial grooves 32 are formed over the entire length in the axial direction on the outer peripheral surface 8d, and a fluid flow path is constituted by the axial grooves 32.
  • a plurality of axial grooves 32 having a small diameter portion 32a on the first thrust bearing portion T1 side and a large diameter portion 32b on the second thrust bearing portion T2 side are arranged at equal intervals in the circumferential direction ( For example, 3) are formed. Since the other configuration conforms to the hydrodynamic bearing device 1 shown in FIG. 10, its description is omitted.
  • the hydrodynamic bearing device 41 shown in Fig. 16 is mainly composed of the sleeve portion 8 constituting the bearing member 27 and the sleeve and the winging portion 29 (49) as separate bodies. Different configuration from device 21.
  • the sleeve portion 8 is formed of, for example, a metal such as brass or aluminum, or is formed of a porous material of sintered metal.
  • the sleeve portion 8 is formed of a sintered metal porous body mainly composed of copper, and the outer peripheral surface 8d thereof is bonded, press-fitted, or pressed into the inner peripheral surface 49a of the housing portion 49. It is fixed by means such as welding.
  • One or more axial grooves 32 are formed on the outer peripheral surface 8d over the entire axial length.
  • a fluid flow path is constituted by the axial groove 32 and the radial groove 25c provided in the contact surface 25bl of the lid member 25.
  • a plurality of axial grooves 32 are formed at equal intervals in the circumferential direction, with the first thrust bearing portion Tl, the side of ⁇ 2 being the small diameter portion 32a and the side communicating with the seal space S2 being the large diameter portion 32b. The case where (for example, three) is formed is illustrated.
  • the housing part 49 has a shape in which the seal part 24 and the housing part 29 shown in FIG. 14 are integrated. Further, instead of the radial groove 24bl shown in FIG. 14, in the illustrated example, a circumferential groove 8cl and a radial groove 8c2 are formed on the upper end surface 8c of the sleeve portion 8, whereby the upper end opening of the axial groove 32 is formed. And the radial bearing gap upper end of the first radial bearing portion R1 are in communication. Since the other configuration conforms to the hydrodynamic bearing device 21 shown in FIG. 14, its description is omitted.
  • a hydrodynamic bearing device 51 shown in FIG. 17 has a sleeve member 8 and a housing portion 29 (59) that mainly constitute a bearing member 27 as separate bodies, and a lid member 25 that seals the lower end of the bearing member 27. Is different from the dynamic pressure bearing device 21 shown in FIG. 14 in that it is integrated with the housing portion 59.
  • the sawing part 59 is formed in a so-called bottomed cylindrical shape with the lid member 25 as the bottom part.
  • a step is provided between the inner peripheral large diameter surface 59a of the housing part 59 and the inner peripheral small diameter surface 59b provided at the lower end thereof, and a radial groove 25c is formed in the axial end surface 59c of the step.
  • the inner peripheral surface of the housing part 59 has a uniform diameter in the axial direction, thereby expanding the area of the first and second thrust bearing surfaces 8b, 25a to the outer diameter side. It can also be taken. Since the other configuration conforms to the hydrodynamic bearing devices 21 and 41 shown in FIGS. 14 and 16, description thereof will be omitted.
  • the bearing members 7 and 27 have different cross-sectional areas (the small diameter portion 32a and the large diameter portion 32b).
  • the same effects as those of the hydrodynamic bearing devices 1 and 21 shown in FIGS. 10 and 14 can be obtained.
  • the herringbone shape is used as the radial bearing portion Rl, R2 and the thrust bearing portion Tl, ⁇ 2.
  • the configuration in which the dynamic pressure action of the lubricating oil is generated by the spiral-shaped dynamic pressure groove is illustrated, the present invention is not limited to this.
  • a so-called step-like dynamic pressure generating portion in which axial grooves are formed at a plurality of positions in the circumferential direction, or a plurality of circular arc surfaces in the circumferential direction are arranged.
  • a so-called multi-arc bearing in which a wedge-shaped radial clearance (bearing clearance) is formed between the outer peripheral surface 2a of the opposing shaft 2 may be employed.
  • the inner peripheral surface 8a of the sleeve portion 8 serving as the radial bearing surface is a perfect circular inner peripheral surface that does not include a dynamic pressure groove or an arc surface as a dynamic pressure generating portion, and is opposed to the inner peripheral surface.
  • a so-called perfect circle bearing can be constituted by the perfect outer peripheral surface 2a of the shaft 2.
  • thrust bearing portions Tl and ⁇ 2 is a force that is not shown in the figure.
  • Thrust bearing surfaces 8b, 9a, and 25a are provided with a plurality of radial groove-shaped dynamic pressure grooves in the circumferential direction. It can also be configured with so-called step bearings or corrugated bearings (step type is corrugated) provided at predetermined intervals.
  • the radial bearing surfaces are formed on the bearing members 7 and 27 side, and the thrust bearing surfaces 8b, 9a, and 25a are formed on the bearing members 7, 27 and the lid member 25 side, respectively.
  • the bearing surface on which these dynamic pressure generating portions are formed can be provided, for example, on the shaft 2, flange portion 2 b, or hub portion 10 side (rotation side) facing them.
  • the communication hole 12 constituting the fluid flow path is not limited to the illustrated position, and can be formed at any position as long as the bearing members 7, 27 are opened on both sides in the axial direction. Further, when the fluid flow path is formed by the communication hole 12 and the radial groove 25c, or the axial groove 32 and the radial groove 25c, it is also possible to provide these on the opposing member side.
  • the axial groove 32 is a force formed on the sleeve portion 8 side. This can also be formed on the housing portions 9, 49, 59 side.
  • the cover member 25 is formed on the housing portion 59 side, and the radial groove 25c is formed in the sleeve portion 8 facing the same. It can also be formed on the side.
  • the fluid channel is configured by the communication hole 12 having the small diameter portion 12a and the large diameter portion 12b or the axial groove 32 .
  • the communication hole 12 that opens on both sides in the axial direction of the bearing member 7 is provided with a region where the cross-sectional area (flow area) gradually increases, for example, a tapered region over a part or the whole in the axial direction.
  • FIG. 18 illustrates a case where a truncated cone portion 12c (tapered region) is provided between the small diameter portion 12a and the large diameter portion 12b of the communication hole 12. This configuration is preferable because the durability of the pin related to the formation of the communication hole 12 can be further enhanced.
  • FIG. 1 is a cross-sectional view showing an example of a motor including a hydrodynamic bearing device.
  • FIG. 2 is a cross-sectional view of a hydrodynamic bearing device.
  • FIG. 3 is a sectional view of the hydrodynamic bearing device.
  • FIG. 4 is a sectional view of the hydrodynamic bearing device.
  • FIG. 5 is a sectional view of the hydrodynamic bearing device.
  • FIG. 6 is a sectional view of the hydrodynamic bearing device.
  • FIG. 7 is a cross-sectional view showing another configuration of the radial bearing portion.
  • FIG. 8 is a cross-sectional view showing another configuration of the radial bearing portion.
  • FIG. 9 is a cross-sectional view of a spindle motor incorporating a fluid dynamic bearing device.
  • FIG. 10 is a sectional view of the hydrodynamic bearing device.
  • FIG. 11 is a cross-sectional view of a bearing member.
  • FIG. 12 is a plan view of the bearing member in which the directional force indicated by the arrow A in FIG. 10 is also viewed.
  • FIG. 13 is a plan view of the bearing member viewed from the direction of arrow B in FIG.
  • FIG. 14 is a sectional view of the hydrodynamic bearing device.
  • FIG. 15 is a cross-sectional view of a hydrodynamic bearing device.
  • FIG. 16 is a sectional view of the hydrodynamic bearing device.
  • FIG. 17 is a sectional view of the hydrodynamic bearing device.
  • FIG. 18 is a cross-sectional view showing another configuration of the fluid flow path.
  • FIG. 19 is a cross-sectional view showing an example of a conventional configuration of a hydrodynamic bearing device.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Sliding-Contact Bearings (AREA)

Abstract

Dispositif palier à pression dynamique de fabrication économique, dans lequel un organe arbre (2) est supporté radialement sur un organe palier (7) en un état sans contact l'un avec l'autre du fait d'une action de pression dynamique provoquée dans le jeu radial du palier entre la surface périphérique extérieure de l'organe arbre (2) et la surface périphérique intérieure (7a) de l'organe palier (7). Le dispositif palier à pression dynamique comprend l'organe arbre (2), l'organe palier (7), un organe de couverture (8) et un organe d'étanchéité (9). L'organe arbre (2) est inséré dans la périphérie intérieure de l'organe palier (7) et la partie ouverte d'extrémité inférieure de l'organe palier (7) est étanchéifiée par l'organe de couverture (8). L'organe d'étanchéité (9) est ajusté sur la partie ouverte d'extrémité supérieure de l'organe palier (7) et un espace d'étanchéité (S) est formé entre l'organe d'étanchéité et la surface périphérique extérieure de l'organe arbre (2). Les rainures de pression dynamique (G) des parties radiales de palier (R1) et (R2) sont réalisées par moulage dans la surface périphérique intérieure (7a) de l'organe palier (7).
PCT/JP2006/308072 2005-04-19 2006-04-17 Dispositif palier a pression dynamique WO2006115104A1 (fr)

Priority Applications (2)

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US11/910,316 US8256962B2 (en) 2005-04-19 2006-04-17 Fluid dynamic bearing device
CN200680012735XA CN101160472B (zh) 2005-04-19 2006-04-17 动压轴承装置及马达

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
JP2005-121253 2005-04-19
JP2005121256A JP4916673B2 (ja) 2005-04-19 2005-04-19 動圧軸受装置
JP2005121253A JP4937524B2 (ja) 2005-04-19 2005-04-19 動圧軸受装置
JP2005-121256 2005-04-19
JP2005-210335 2005-07-20
JP2005210335A JP2007024267A (ja) 2005-07-20 2005-07-20 流体軸受装置およびこれを備えたモータ

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JP2011002024A (ja) * 2009-06-18 2011-01-06 Nippon Densan Corp 軸受装置、スピンドルモータ、及びディスク駆動装置
JP2011133105A (ja) * 2009-11-25 2011-07-07 Nippon Densan Corp 動圧軸受およびそれを用いたスピンドルモータ
JP5892375B2 (ja) 2011-06-30 2016-03-23 日本電産株式会社 動圧軸受装置およびファン
KR101240742B1 (ko) * 2011-09-22 2013-03-11 삼성전기주식회사 베어링 어셈블리 및 이를 포함하는 모터
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JP2013085447A (ja) 2011-09-30 2013-05-09 Nippon Densan Corp モータおよびディスク駆動装置
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JP2014005933A (ja) 2012-05-30 2014-01-16 Nippon Densan Corp 軸受機構、モータおよびディスク駆動装置
JP5812351B2 (ja) 2012-05-30 2015-11-11 日本電産株式会社 軸受機構、モータおよびディスク駆動装置
KR101434020B1 (ko) * 2012-07-04 2014-08-25 삼성전기주식회사 스핀들 모터
JP2014023205A (ja) 2012-07-13 2014-02-03 Nippon Densan Corp モータおよびディスク駆動装置
JP2014059009A (ja) 2012-09-18 2014-04-03 Nippon Densan Corp 軸受装置、スピンドルモータ、およびディスク駆動装置
JP2014059008A (ja) 2012-09-18 2014-04-03 Nippon Densan Corp 軸受装置、スピンドルモータ、およびディスク駆動装置
US8773816B1 (en) 2013-03-13 2014-07-08 Nidec Corporation Spindle motor with hydrodynamic bearing structure having capillary seal and disk drive apparatus including same
US8941946B2 (en) 2013-03-14 2015-01-27 Nidec Corporation Motor including dynamic bearing with seal portion and disk drive apparatus including the same
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US20090129710A1 (en) 2009-05-21
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